Steam boiler



M. H. KUHNER Nov. 14, 1933.

STEAM BOILER Filed Jan. 4, 1932 3 Sheets-Sheet 1 a 0A 0 O O O 0 M 0 O Q 6m 0/ o L O O 67 gOOOOOO INVENTOR Zg AX H. KUHNER AT-TO'RNEY- oo ooooom .oooooo l .000000' Nov. 14, 1933. M. H. KUHNER STEAM BOILER Filed Jan. 4, 1932 3 Sheets-Sheet 2 v m i l U W AM 2 W gm @W STEAM BOILER Filed Jan. 4. 1952 5 Sheets-Sheet 3 INVENTOR MAX H. KUHNER BY Wfi H x ATTORNEY Patented Nov. 14, 1933 UNITED STATES STEAM BOILER Max H. Kuhner, Worcester, Mass, assignor, by

mesne assignments, to Riley Stoker Corporation, Worcester, Mass, a corporation of Massachusetts Application January 4, 1932. Serial No. 584,631

5 Claims.

This invention relates to. steam boilers, and more particlularly to boilers of the .water tube type adapted for the generation of steam at very high pressures. g 1

The cylindrical drums or shells of high pressure boilers must have very thick walls in order to provide the necessary strength to withstand the pressure, particularly when the walls are weakened by closely spaced tube holes. Such drums, to comply with safety requirements, must ordinarily be of seamless construction and forged from a single block of steel, so that they are extremely expensive. Moreover, when'su'ch a drum is exposed to high temperature furnace gases it is likely to be damaged, since the great thickness of metal prevents the rapid conduction of the heat to the water within the drum. As a result, the outer surface of the drum will reach a temperature considerably in excess of the water temperature, and may either be burned by the heat or cracked because of the diiferences in expansion and the resultant tremendous internal stresses in the metal.

In a high pressure boiler the water is necessarily at a comparatively high temperature and. hence has less cooling effect on the heat exposed tubes. Moreoven'the volume of the steam is much less in proportion to its weight than in low pressure boilers, and as a result the circulation tends to be more sluggish. Since steam is a very poor conductor of heat, it is essential that the steam bubbles be swept along as soon as they are formed, for if such a steam bubble remains stationary and in contact with the metal for an water circulating path independent of the drum. circulating system. The tubes 12 and were conno appreciable length of time, the metal is very likely to become overheated. From these facts, it follows'that in a high pressure boiler it is of the greatest importance to maintain rapid and continuous circulationof the water and steam, and to avoid any restrictions in the path of flow which would tend to retard the circulation or cause steam locking of the heat exposed tubes.

It is accordingly one object of the present invention to provide a steam boiler having a single steam and water drum which is not exposed to high temperature furnace gases.

It is a further-object of the invention to provide a steam boiler having rapid and unrestricted circulation, and comprising a single steam and water drum which is not weakened by closely spaced tube holes. I

It i a further object of the invention to provide a steam boiler having a single steam and water drum and means forming a continuous It is a further object of the invention to provide a steam boiler which will be comparatively inexpensive to construct and efficient inoperation, and which is particularly suitable for the generation of very high pressure steam.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

In accordance with my invention, I provide a boiler having water tubes connected in series to form a complete circulating system, and a steam and water drum located outside of the circulating system and unexposed to the hot gases flowing through the boiler. The steam generated in the water tubes is preferably delivered to the drum. The feed water for the boileigmay be supplied to the drum, and may flow therefrom into the main circulating system. The water tubes are preferably arranged in banks which are connected at their ends by means of seamless steel headers located in vertical planes and arranged in close contact laterally. These headers may be straight, or they may be bent intermediate theirlength so that the tubes of each bank may be straight and all of the same length. In case the headers are straight, the tubes may likewise be straight and enter the headers at an acute angle, or the tubes may be bent at-their ends to enter the headers in a direction perpendicular thereto. Water wall tubes may be provided to absorb radiant heat from the furnace, and these tubes may discharge steam either into the main circulating system of the boiler, or directly to the steam and water drum.

Referring to the drawings illustrating one embodiment of the invention, and in which like ref-'- erence numerals indicate like parts,

Fig. 1 is a sectional side elevation of a steam boiler and combustion chamber;

Fig. 2 is a partial section on the line 2-2 of Fig. 1;

Fig. 3 is a section on the line 3-3 of Fig. 1;

Fig. 4 is a sectional side elevation of one of the side water walls and associated parts;

Fig. 5 is a sectional side elevation of a modified form of boiler, the superheater and water walls being omitted for simplicity of illustration; and

Fig. 6 is a View. similar to Fig. 5, showing a fur ther modification.

The embodiment illustrated in Figs. 1 to 4 in- 11 and 12 connected in series to form a complete nected by a group of headers 14, preferably of seamless steel and approximately square in crosssection. In a similar manner, the tubes 10 and 11 are connected by a group of headers 15, and tubes 11 and 12 are connected by a group of headers 16. These various headers are located in vertical planes, and the headers of each group are arranged in close contact laterally, as shown in Fig. 2. The internal cross-sectional area of each header is preferably substantially equal to the sum of the internal cross-sectional areas of the tubes in the vertical row connected thereto. For example, if there are seven tubes in each vertical row, as in the embodiment illustrated, each header should provide nearly seven times the area of a single tube, so that there will be no undue restriction on the circulation from one tube bank to the next. Hand hole caps 18 may be provided on the headers to allow access to the interior thereof. Each of the headers is bent intermediate its length through an angle equal to the angle between the adjacent tube banks so that the tubes are perpendicular to the headers. With this construction, the tubes in each bank are straight and of the same length.

The rear tube bank 12 is substantially vertical, whereas the lower tube bank 10 slopes upwardly toward the front, and the upper tube bank 11 slopes upwardly toward the rear. The boiler is installed with the lower tubes 10 directly above a furnace combustion chamber 19, and baffles are arranged to direct the hot gases across the tubes 10, 11 and 12 in the order named. For this purpose I provide a baffle 21 sloping upwardly and forwardly from the central portion of the header group 14 to the lower row of tubes in the bank 11 at a point intermediate the length thereof. A second baffle 22 slopes downwardly and rearwardly from the upper end of baffle 21 to the front row of tubes in the bank 12, and a third baffle 23 extends down- Wardly from the header group 16 through the central portion of the tube bank 12 to a point spaced above the header group 14. An uptake or gas outlet duct 25, having a damper 26 therein, is connected to the upper rear portion of the rear tube bank 12. Doors 27 may be provided in the side walls to allow access to the space enclosed by the tube banks. A soot blower 29 and soot hopper 30 may be provided at the lower portion of the rear tube bank 12 to permit removal of any soot or fly ash which may ac- (ill cumulate on the upper surfaces of the headers 14.

The furnace chamber 19 may be fired in any suitable manner, as by means of pulverized coal.

For this purpose, I have provided aburner opening 32 in the front wall 33 of the furnace. An ash removal door 34 may also be provided in this wall.

In order to collect the steam generated in the heat exposed tubes and provide a reserve supply of water to take care of sudden demands for steam, I utilize a steam and water drum 36 which is located outside of the main circulating system and which is unexposed to the hot gases. This drum is preferably shaped as a horizontal cylinder located above the header'group 16 and extending transversely thereof. The headers 16 are connected at their upper ends to the steam space of the drum 36 by means of tubes 37, and at their lower rear ends to the water space of the drum by means of tubes 38. Feed water may be supplied to the drum through a nozzle 40, and steam may be withdrawn from the drum through tubes 41. These tubes 41 may be rather widely spaced, and

the tubes 37 and 38 may be staggered adjacent to the drum, so that the drum will not be greatly weakened by the tube holes, and the drum walls need not be as thick as would otherwise be the case.

The tubes 41 lead to a horizontal superheater inlet header 43 mounted above and transverse to the tube bank 11. An outlet header 44 is mounted adjacent to the inlet header 43, and the two headers are connected by superheater tubes 45 shaped to provide an extensive superheating surface located in the triangular space defined by the baffle 21 and the tube banks 10 and 11. The superheater 45 protects the baffle 21 to a considerable degree from the hot gases.

In many cases it is desirable to utilize Water tubes adjacent to the walls of the combustion chamber to absorb radiant heat from the flame, thereby reducing the furnace temperature and at the same time protecting the walls from the heat. Such water walls may be utilized in connection with the boiler construction heretofore described. At the bottom of the rear wall of the furnace I have shown a horizontal header 47 from which spaced water tubes 48 extend upwardly to the lower ends of the headers 14, there being one tube for each header. A similar construction may be utilized at the furnace front, where I have shown a horizontal header 49 from which tubes 50 extend upwardly to the lower ends of the headers 15. At each side of the furnace I have pro vided a lower horizontal header '52 connected to an upper horizontal header 53 by closely spaced vertical tubes 54.

The header 47 is supplied with water'by means of a row of tubes 56 extending downwardly thereto from the rear portions of the headers 16. These tubes are located immediately in the rear of the tube bank 12, and in the embodiment illustrated they are exposed for a part of their length to the gases flowing through the boiler. However, these gases are considerably reduced in temperature before they reach this part of the boiler, and such heat transfer as does take place has .no serious effect on the circulation. The lower side wall erated therein, I have provided a header 60 (Fig.

4) at each side of the furnace which is of the;

same shape as the headers 15 and which is located laterally adjacent thereto. I have also provided a header 61 at each side of the furnace which is of the same shape as the headers. 16 and which is located laterally'adjacent to these headers.

The upper side water wall headers 53 are con nected to the headers 60 by means of tubes 63, and to the headers 61 by means of tubes 64. The headers 60 and 61 are connected to each other by means of tubes 65. The rear end of each head- 1 'er 61 is connected to the rear endof the corre- 'sponding header 52 by tubes 67.- The water space of the drum 36 is connected to the rear portion of each header 61 by a tube 68, and the steam space of the drum is connected to theupper por- 1;

ber 19. The water wall tubes 48, 49 and 54 absorb radiant heat from the combustion flame and generate steam while protecting andcooling the furnace walls. The hot gases flow past the tube bank 10, the superheater 45, the tube bank 11, and the tube bank 12 to the uptake 25, producing a rapid circulation of the water and steam upwardly in tube banks 10 and 11, and downwardly in tube bank 12. This circulation is not materially restricted at any point, and is independent of the drum 36. Feed water is introduced into the drum and fiows downwardly through tubes 38 intothe rear tube bank 12. Because of this feed water, and also because of the low gas temperature in the rear portion of the boiler, very little if any steam is generated in the tubes 12. 'As a result these tubes are filled with water unaccompanied by steam bubbles, and the downward circulation is very rapid. Steam produced in the tubes 10 and 11 flows through the tubes 37 to the drum 36, where any entrained'moisture is deposited, and the dry steam flows through the tubes 41 and superheater 45 to the outlet header 44. The circulation through the water Wall tubes is also independent of the drum. The flow is downward in tubes 56 and 67, and upward in tubes 48, 57, 54, 58, 50, 63, 64 and 65. Feed water flows downwardly through tubes 68, and steam from the side water walls enters the drum through tubes 69.

In Fig. 5 I have shown a modification in which straight tubes and straight headers are utilized for the main circulating system. This embodiment comprises three banks of Water tubes 71, 72 and 73 connected at their: ends by header groups 75, 76 and 77. The tubes enter the headers at an acute angle. Baflies' 78, 79 and 80 are provided to direct the gases through the boiler and to an uptake 82 having a damper 83. A soot blower 84 and soot hopper 85 are provided at the bottom of the rear tube bank 73.

A steam and water drum 87 is mounted abovethe headers '77 and connected thereto by steam tubes 88 and Water tubes 89. Steam leaves the drum through tubes 90.

In Fig. 6 I have shown a furthermodification utilizing straight headers, the tubes of the main 92, 93 and 94 connected at their ends by header water tubes, three groups of headers connecting -the banks of water tubes in series to provide a groups 96, 9'7 and'98. Bafiles 100, 101 and 102 are provided to direct the gases through the boiler and to an uptake 104 having a damper 105. A soot blower 106 and soot hopper 107 are provided at the bottom of the rear tube bank 94. A steam and water drum 109 is mounted above the headers 98 and connected thereto by steam tubes 110 and water tubes 111. Steam leaves the drum through tubes 112.

The embodiments illustrated in Figs. 5 and 6 operate in substantially the same manneras the construction shown in Fig. 1, so far as the generation of steam in the main circulating system is concerned. tinuous circulation is'maintained independent of the steam and water drum, and the latter is neither exposed to the hot gases nor weakened by a multiplicity of closely spaced tube holes. Since there is but a single drum, the cost of the construction for very high pressures is greatly reduced in comparison with prior constructions utilizing several drums.

In each case a rapid and con- Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A steam boiler comprising a substantially vertical rear bank of water tubes, an upwardly tubes, three groups of headers connecting the tube banks in series to form a circulating system, each header being located in a vertical plane, and the headers of each group being closely adjacent to one another laterally, means to pass hot gases into contact with the water tubes, a transverse steam and Water drum mounted above the upper group of headers and outside of the path of the hot gases, and tubes connecting said drum with the headers of said upper group.

2. A sleam boiler comprising a substantially vertical rear bank of tubes, an upwardly and forwardly-sloping bank of Water tubes. an upwardly and rearwardly sloping bank of Water tubes, three groups of headers connecting the tube banks in series to form a circulating system, each header being located in a vertical plane, and theheaders of each group being closely adjacent to one another laterally, means providing a gas outlet connected to the upper rear portion of the rear tube bank, means to pass hot gases into contact with the water tubes and thence into the gas outlet, a transverse steam and water drum moiuited above the upper group of headers and outside of the path of the hot gases, tubes connecting said drum with the headers of said upper group, a soot hopper in the rear of and adjacent to the lower end of the rear tube bank, and a soot blower arranged to blow into the hopper soot which may accumulate on the upper surface of the lower header group. a

3. A steam boiler comprising three banks of water tubes, three groups of headers connecting the banks of water tubes in series-to provide a circulating system, the headers of each group being bent intermediate their length through an "angle equal to the angle between the adjacent tube banks, whereby the tubes of each bank are all of the same length and perpendicular to the headers, means to pass hot gases into contact with the water tubes, a steam and water drum located outside of the path of the hot gases, and connections between one of said header groups and the drum.

4. A steam boiler comprising three banks of circulating system, the headers and the tubes of each bank being straight, and the tubes entering the headers at an acute angle, means to pass hot gases' into contact with the water tubes, a steam and Water drum located outside of the path of the hot gases, and connections between one of said header groups and the drum.

' 5. A steam boiler comprising three banks of water tubes, three groups of headers connecting the banks of water tubes in series to provide a circulating" system, the headers being straight and the water tubes being bent at their ends to enter the headers at right angles, means to pass hot gases into contact with the water tubes, a steam and water drum located outside of the path of the hot gases, and connections between one of said header groups and the drum.

. MAX H. KUHNER. 

